python 33 lines · 7 steps

Handling a post form with a Flask Blueprint

A Blueprint route validates a WTForms form, saves a new post, and redirects on success.

Explained by highlit
Flask Intermediate blueprints form-validation post-redirect-get authentication orm
1from flask import Blueprint, render_template, redirect, url_for, flash
2from flask_login import login_required, current_user
3from flask_wtf import FlaskForm
4from wtforms import StringField, TextAreaField, SubmitField
5from wtforms.validators import DataRequired, Length
6 
7from .models import db, Post
8 
9bp = Blueprint("posts", __name__, url_prefix="/posts")
10 
11 
12class PostForm(FlaskForm):
13 title = StringField("Title", validators=[DataRequired(), Length(max=140)])
14 body = TextAreaField("Body", validators=[DataRequired(), Length(min=10)])
15 submit = SubmitField("Publish")
16 
17 
18@bp.route("/new", methods=["GET", "POST"])
19@login_required
20def create():
21 form = PostForm()
22 if form.validate_on_submit():
23 post = Post(
24 title=form.title.data.strip(),
25 body=form.body.data.strip(),
26 author=current_user,
27 )
28 db.session.add(post)
29 db.session.commit()
30 flash("Your post has been published.", "success")
31 return redirect(url_for("posts.detail", post_id=post.id))
32 
33 return render_template("posts/new.html", form=form)
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Blueprints group related routes under a shared URL prefix so features stay modular.
  2. 2validate_on_submit collapses the GET-render and POST-handle branches into one clean function.
  3. 3Redirecting after a successful POST prevents duplicate submissions on browser refresh.

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